Diesel engines typically have a series of coolant passages surrounding a cylinder that extends parallel to the cylinder through the engine block and head. A gasket or plate is usually employed between the head and the block to prevent the escape of combustion gasses. Special provision such as a raised rib surrounding a cylinder is sometimes provided to assure that an adequate seal is formed with respect to the combustion products. However, typically a simple fiber ring seal is provided for preventing the leakage of coolant from the coolant passages. Such seal is usually positioned within a hole formed in the gasket or plate so that the interior of the fiber seal is approximately aligned with the coolant port. The fiber seals have been reasonably effective, but there have been leakage problems and there is always a need to improve the reliability of such.